When a user directs a web browser to a website, the web browser may receive a request to install a cookie. A cookie may be a short text file that is associated with the domain name of the website that sets the cookie on the user's web browser. When the web browser with the stored cookie returns to the website that installed the cookie, the web server associated with that website may receive the cookie and use the information included in the text file. The information in the cookie may be used to customize a web page or for other operations that may be accomplished with information about the user or the user's browser.
Often a user may visit a website and receive a request to install a cookie from a domain name that is not the website to which the user had directed its browser. This request by a third-party to have its third-party cookie installed on the user's web browser may be unknown to the user. A third-party cookie may pose a threat to the privacy of the user by allowing a third-party to track the browsing and site interaction habits of the user in a way that is invisible to most users. The level of threat may depend on the third-party's intended use of the information it collects through its third party cookies.